The scientific community (at least the majority) recognizes the existence of climate change. And not only that: a non-negligible part of the members believe that the phenomenon moves with such great inertia that it will hardly be possible to do anything to reverse it; in any case it will be necessary to minimize it. In this group is Corrado Altomare (Terlizzi, Italy, 1981). This civil engineer and researcher Ramón y Cajal from the UPC School of Roads aims to develop a model that helps predict how urban coastal defenses will respond to extreme wave conditions under various future climate scenarios. And the BBVA Foundation has just awarded him one of the Leonardo scholarships (which turn ten this year) to make it a reality.
What does the project consist of?
To characterize the flows of water masses from the wave over structures that we technically call overtopping, that is, the flow of water that passes over a coastal structure, such as a promenade, and that can cause damage to people, buildings and floods. We are clearly facing climate change. We have already experienced weather phenomena such as Gloria in January 2020, a type of storm that will become more frequent and intense. And we are no longer talking about a question of the resistance of the coastal system, but of resilience. You may weather the first storm, the second too, and the third. But what about the fourth?
Can they quantify what overshoots climate change will bring?
It is the first thing we want to calculate, to be able to determine what awaits us: what water flows we are talking about, volumes, speeds and damage that we can have if we do not intervene.
In Spain, which are the most vulnerable areas?
The Basque Country The whole area of the Cantabrian is faced with waves of great intensity, much bigger and more frequent than in the Mediterranean. However, the Mediterranean area is also sensitive: you only have to look at what caused the Gloria, which left maximum waves of seven meters, or even a little more depending on the locality. In the Cantabrian, however, you can reach 14 meters.
The double?
Yes, and it's a longer wave, with a longer period. The longer a wave is, the faster it is and the more likely it is to cause overtopping. I explain to my students that a longer wave resembles a tsunami, if we take it to the extreme. It is less affected by what happens below. It is so big that, even if it finds something in the depths, it easily makes its way up the beach. A tsunami sweeps away everything because it is a wave the size of kilometers and has a lot of momentum.
The methodology they intend to create would be a good prevention tool.
Of course. If we have the forecast of the possible rise in sea level and the height of the waves that a storm could bring, we could determine, once we have the methodology ready, the overshoot that could occur and its effects. With this information, the competent authority can make decisions to protect the promenades and the public. For example, modifying the geometry of the ride.
Is there any population that has taken measures of this kind?
I worked for many years in Belgium. There the situation is more sensitive because the country is below sea level. In one of the towns (Wenduine) modifications were made to protect the promenade. However, if you go to the village and walk along the seafront, it doesn't seem like there has been any action. Because? Because the modification consists of two benches where people sit and do not know that they have a function, also during storms. They are two benches with a backrest each of about 80 cm and separated by 11 meters. What they do is slightly increase the protection height of the promenade and causes the waves, in the context of a major storm, to impact it, dissipating energy. All this reduces the impact.
Are the boardwalks in danger?
It depends on the area, but they may be there. Especially in cases where there is a lot of beach erosion and maybe, afterwards, it doesn't regenerate. The fact that there is no beach means more interaction of the waves with the structures of the promenade and with bigger waves. And this can be more critical when you have a vertical structure, because, in addition, more erosion can be generated at the base and it can end up collapsing.
It becomes essential, then, to regenerate the beaches.
In general, a very wide or very long beach dissipates more energy, because the wave breaks. But there is also a limit to regeneration. There may be areas where it cannot be done because it is expensive, or because there is no sand nearby that can be used. In these situations, you need to think of other solutions.
There are underwater structures that can help with that as well.
Yes. For example, a breakwater slope, of a determined and studied size, which is not visible from the beach, because it is submerged. When the wave arrives, it interacts with the barrier, undergoes a somage process (rises), breaks, dissipates its energy and protects the beach.
Are you optimistic about curbing climate change?
I am very skeptical. I think we have already entered a trend and we have not acted in time. And the context doesn't help either, with the wars going on around the world. We are investing in other things. The trend of climate change is very difficult to reverse. For this reason, we must invest in protecting ourselves, and also in causing less damage, investing in renewable energies. We can combine the two.
And move away from the coast?
A possible alternative, although we will never carry it out, is to move the city. I mean, let the sea do what it has to do. If he has to erode the beach because it is not natural, let him erode it. It's a controversial approach, I know. In theory, this option exists, although it has a great economic impact: there is infrastructure, business, tourism...
